Crane control system



May 13, 1952 R. w. SPAFFORD CRANE CONTROL SYSTEM 3 Sheets-Sheet l Filed April 17, 1948 L- wn SN vmmmamu W. NT

N @Lw May 13, 1952 R. w. SPAFFORD CRANE CONTROL SYSTEM 5 Sheets-Sheet 2 Filed April 17, 1948 Ralph ZHSZZYfl-z QH i NS R. w. sPAFFoRD 2,596,347

CRANE CONTROL SYSTEM 5 Sheets-Sheet I5 Filed April 17, 1948 May 13, 1952 Patented May 13, 1952 CRANE CONTROL SYSTEll/I Ralph W. Spafford, Fairfield, Iowa, assigner to The Londen Machinery Company, Fairfield, Iowa, a corporation of Iowa Application April 17, 1948, Serial No. 21,601

(Cl. 10S- 163) 11 claims. 1

This invention relates to crane systems and crane control apparatus, more particularly to crane systems wherein the crane may have both longitudinal to and fro movements and transverse to and fro movements on suitably provided runways, and it is an object of the invention to provide improved crane control apparatus for such systems.

In crane systems of the character indicated, a pair of parallel spaced apart runways are usually provided upon which a transverse or crane bridge is adapted to run, and a crane proper is also provided for running upon the transverse bridge. The bridge moving on the runways produces longitudinal to and iro movements of the crane and may be termed runway travel, and the crane moving on the bridge produces transverse to and iro movements thereof and may be termed bridge travel. Suitable spur runways may be arranged at intervals with which the transverse bridge may come into registry so that the crane may run off of the bridge and onto a spur. The crane proper, in addition to means for producing transverse to and fro movements, may include apparatus for raising and lowering operations. rihe bridge runways upon which the bridge moves, and the spur runways upon which only the crane proper moves, may be suspended from a ceiling or otherwise suitably mounted in any desired and well understood manner.

Electric power, for example three-phase alternating current, 60cycle power, advantageously may be used, one electric motor being mounted on the bridge for producing runway travel, a second motor being associated with the crane for producing transverse movements thereof or bridge travel, and a third motor being associated with the crane for producing hoisting and lowering movements.

In the operation of crane systems such as described, there is relative movement between the crane proper and the motor for driving the bridge while the crane is on the bridge, as well as when the crane is operating upon a spur runway. This may require that separate control stations be proper and the control station which may interfere with the operation and necessarily limits the distance to which a crane may move off of the bridge and onto a spur runway, or they may take the form of a pair of bus bars on the bridge upon which collectors run. In the latter case, the collectors remain flapping in the air when the crane runs onto a spur runway since no control is then needed for the longitudinal runway travel and no separate bus bars need be provided.

Accordingly, it is a further object of the invention to provide improved control apparatus for a crane system wherein movements of the crane bridge along the runways (i. e. runway travel), movements of the crane on the bridge (bridge travel) and on the spur runway, and hoisting and lowering movements of the crane are controlled from a single station associated with the crane.

It is a further object of the invention to provide improved control means for a crane system of the character described wherein the same bus bars or conductors supplying power to the bridge travelmotor supply power for controlling this motor, as well as for controlling the runway travel motor.

It is a further object of the invention to provide improved means for controlling a crane system of the character described that is efcient in operation, simple in character, and may be operated by one man.

In carrying out the invention in one form, crane apparatus including a pair of spaced apart runways, a crane bridge for running thereon and a crane for running on the bridge are provided together with spur runways with which the bridge may come into registry and onto which the crane may also run. A three-phase power supply is used in which two conductors or bus bars are provided, the third being a ground connection including the runways and bridge. Bus bars on the bridge are connected by collectors to the power supply bus bars through a pair of current responsive devices which control energization circuits which in turn control the runway travel motor. Power to the bridge travel motor is 'supplied throughthe bridge bus bars as is the control current therefor. When this motor is energized at a control station on the crane, both the responsive devices function and coact to prevent energizaticn of the means controlling runway travel. The runway travel motor is supplied with power from the supply not iiowing through the responsive devices, but the control therefor is such that connecting one of the bridge bus bars to ground by the control station energizes one of the current responsive devices, which in turn effects energization of circuits controlling runway travel.

For a more complete understanding of the invention, reference should be had to the accompanying drawings in which:

Figure 1 is a front View of crane apparatus embodying the invention;

Fig. 2 is an end view taken substantially in the direction of arrows 2--2 of Fig. l;

Fig. 3 is a schematic View of a cre-ne system embodying the invention;

Fig. 4 is a wiring diagram somewhat schematic of the elements shown in Fig. l;

Fig. 5 is a simplified wiring diagram corres1 sponding to the wiring diagram of Fig. 4, and

Fig. 6 is a further simplified wiring diagram illustrating the manner of operation of the invention.

Referring to the drawings, the invention is shown embodied in a crane system IS comprising, a pair of spaced apart runways II and I2, a crane bridge I3 for running thereon, a crane I4 for running on the crane bridge, and a spur runway I5 arranged to have the crane bridge come into registry therewith so that crane I4 may move oir the bridge and onto the spur. In the schematic views of Figs. 3 and e, a second spur runn way I6 is shown.

Runways II and I2 are shown as I beams susn pended from a roof or ceiling by means of rods I1 and I8, the crane bridge being adapted to run on the lower anges of the I beams. Likewise, spur runway I5 (and other spur runways) may comprise an I beam suspended from the ceiling or roof by a series of rods I9, the crane being adapted to run on the lower flanges thereof. It will be understood that the particular construction of the runways and the manner of suspending them is exemplary and that other arrangements of runways may be used.

Crane bridge I3 may comprise a transverse beam 2| rigidly attached, such as by welding or clamps for example, to a pair of spaced apart and longitudinally extending channel members? 22 and 23 at one end, and 2li and 25 at theother. At each end of the channel members therev are brackets attached, such as by welding, upon which brackets pairs of rollers are mounted for riding upon the lower flanges of runways i I i2. See for example Fig. 2 wherein brackets 2i; and 21 are attached to channel member 24, and pairs of rollers 28 and 29 mounted thereon respectively ride upon the lower flanges of runway II. Mounted atop beam 2| may be a second beam 3I to provide additional rigidity and support for the crane bridge. While the crane bridge has been described as constructed of beams and channel members, it will be understood that other shapes and forms may be used as Well as other modes of construction so long as sufficient rigidity and strength are had.

Mounted upon beam 3I is an electric motor which drives a shaft 33 by means of a chain and sprockets, shaft 33 driving a pair of rubber tired wheels and 3S, which in turn engage the lower surface of runways I I and I2 for driving the crane bridge therealong. Shaft 33 is supported by the crane bridge in bearings which may be mounted in any manner well understood in the art.

Collectors 31 and 35' may be insulatingly carried by beam 3| and are adapted to engage respectively a pair of conductors 39 and 4I of a three-phase, 60cycle power supply (L1, L2, La),

for example, the third conductor thereof (L3) being runways II and I2, bridge member 2|, and spur trackways i5 and I5 inasmuch as all of these members are grounded. Insulatingly carried by brackets 42, 43 and 44 are conductors 45 and 43 extending along bridge member 2| for supplying power to crane I4. Similarly, a pair of conductors d1 and 48 are insulatingly carried alongside runway I5 by brackets 49 and 5I for supplying power to crane i4 while on the spur runway. Other types of three-wire power sources may of course be used.

Crane Id may comprise one part including a motor for towing or pushing the crane from one position to another on the spur runways and on the bridge, and a part 53 for raising and lowering the hook 54, motor 55 being adapted to drive a rubber tired member 56 which engages the lower surface of beam 2I and the lower surfaces of the various spur runways. Part 52 is suspended from beam 2I by yoke members 51 and 53 upon which are mounted rollers for riding upon the lower flange of the bridge and spur runways. Part 53 comprises a hoist motor 6I and the associated hoist gears (not shown) carried by a support 62 and pairs of rollers 63, 64, and G5, 66 adapted to run upon the lower iiange of beam 2I. Towing part 52 is connected to hoisting part 53 by any toggle means, such for example as a link 61. Current collectors 6B and` $9 are carried by the combination for engaging conductors i5 and 4S for supplying power to motors 55 and 6I. While towing part 52 and hoisting part 53 have been generally described, it will be understood that other arrangements may be used.

Runway travel motor 32, bridge and spur runway travel motor 55, as well as hoist motor 6I, are controlled from a single station 1I on crane i4, which for example may be a series of push button switches. That is to say, when crane I4 is on a spur trackway, the hoisting and traveling movements are controlled from station 1I, and when crane id is on the bridge the hoisting and bridge travel movements, as well as the runway travel movements, are controlled from this same station.

With the foregoing structure in mind, the remaining structure and circuit arrangements for producing complete crane control from a single station by one man may now be described.

Referring to Figs. 4, 5 and 6 showing the crane and control apparatus therefor schematically, runway travel motor 32 is connected to collectors 31 and 38 by either one of a pair of contactors 12 and 13, depending upon the direction of runway travel, and bridge travel motor 55 is connected to collectors 58 and 69 by either one of a pair of contactors 14 and 15 depending upon the direction of operation. The various push buttons of control station 1I are connected to collectors 68 and 59 and to ground, and thus derive their ability to control motors 32, 55 and 5I (Fig. 1) from collectors 68 and 63 which move with crane I4, even though motor 32 is connected to collectors 31 and 38 which are stationary on the bridge.

To control motor 32 from'station 1I, a pair of current sensitive devices or relays 8| and 32 are connected in circuit between conductors 45 and 46 and collectors 31 and 38 so that all power reaching conductors 45 and 46 must do so through relays 8| and 82. Relays 8| and 82 are energizable on small currents as well as large currents, and are adapted, when both are energized-to prevent the operation of contacters 12 and 13, thereby preventing energization of motor 32. But when one or the other only of relays 8| and 8| is energized, a corresponding one of contacters 12 and 13 is operated to supply power to motor 32. `As will be more particularly described subsequently, relays 8| and 82 in series are connectable in circuit with either one of the actuating coils of contacters 14 and 15 and collectors 88 and 69 for energizing both relays. In this situation one of contacters 14 and 15 is operated to supply power to motor 55, but contacters 12 and 13 are prevented from being energized. Similarly, relays 8| and 82 are adapted to be connected respectively in circuit between collector 31 and ground and collector 38 and ground. Thus, relays 8| and 82 may be energized one at a time, and when this is done one of contacters 1'2 and 13 is operated te supply power to motor 32. Consequently control of runway travel, bridge travel, and hoisting is obtained from a single station by virtue of the provision of a pair of relays, both of which are energized when bridge travel or hoisting is to take place to prevent runway travel, and when runway travelI is desired only one of the two relays is energized.

The circuits for producing these functions may new be described. Power is supplied to conductors or bus bars 45 and 46 carried by the crane bridge from-bus bars 39 and 4| from, respectively, collector 31 running on bus bar 39, through conductors 83 and 84, coil 85 and reactor 86 of relay 8|, and conductor 81 to bus bar 45; and from collector 38 running on bus bar 4|, through conductors 88 and 89, coil 9| and reactor 92 of relay 82, and conductor 93 to bus bar 46. Thus, bus bars 45 and 46 are energized at all times when bus bars 39 and 4| are energized through the coils and reactors of relays 8| and 82.

When bridge travel motor 55 is to be energized for moving the crane forward en the bridge, push button 94 is pushed to close its contacts, thereby energizing coil 91 of contacter 14 through the following circuit: From bus bar 45 through collector 68, conductors 95 and 95, push button switch 94, coil 91, conductors 98 and 99 to collector 69. Completing a circuit through coil 91 by means of push buttom 94 completes, at the same time, circuits through coil 85 and reactor 86, and coil 9| and reactor 92 of relays 8| and 82 through the circuits previously described for these members inasmuch as any energy on bus bars 45 and 46 must come from collectors 31 and 38 through relays 8| and 82. Energizing coil 91 causes this coil to close contacts |0|, |82, and |03 of contacter 14, thereby supplying power to motor 55 from bus bars 45 and 48 through conductors 95 and 99. Contact |02 is connected to ground, as shown, for completing the motor power circuit. Motor 55 being energized, it rotates wheel 56 '(Fig. 1) against the bottom of beam 2| thereby moving crane |4 forwardly or toward the right. This movement is stopped by releasing push button 94 whereupon coil 91 becomes deenergized and contacts |02 and |03 open.

Inasmuch as the power current for motor 55 ows through relays 8| and 82, it is desirable that there be only a small voltage drop therethrough in order that full voltage will be applied to the motor and there will be only small losses through the relays. Accordingly, coils 85 and 9| are constructed with relatively low resistance and the proper number of turns so that the coils willpick up their contacts on relatively small currents, for example as low as one-quarter of an ampere. When current for motor 55 is flowing, a certain proportion of this current iiows through coils and 9|. However, reactors 86 and 92 shunting, respectively, coils 85 and 9| are of the saturable character whose impedance decreases very materially when current ilew becomes large. The impedance of these members decreases sufficiently so that the total current through the coils and the reactors flows without appreciable voltage drop whereby the operation of motor 55 is unimpaired. Currents as large as 50 amperes may flow through relays 8| and 82 when motor 55 is operating.

While not illustrated on the schematic Figs. 5 and 6, the crane will operate in the reverse direction upon the bridge by using push button ||6 which completes a circuit for coil ||1 of contacter 15 as follows (Fig. 4): From collector 68 through conductors 95 and 96, push button switch IIS, conductor I|8, coil ||1, conductors ||9, 98 and 99 to collector 69. Energizing coil ||1 closes contacts |2|, |22 and |23, contacts |2| and |23 being connected respectively to conductors 99 and 95, whereas contact |22 is connected to ground. These connections reverse, the two conductors leading to motor 55 thereby causing it to revolve in the reverse direction, as is well understood in three-phase circuits.

Coils 85 and 9| of relays 8| and 82 being energized by closing push button 94, contacts |04 and |05 associated therewith, respectively, are closed thereby completing circuits for energizing coils |06 and |01 respectively of relays |08 and |09 as follows: From collector 31 through conductor 83, conductor coil |06, conductor l2, closed contacts |04, conductor ||3, and conductor 88 to collector 38; and from collecter 31 through conductor 83, conductor |4 (including conductor I of Fig.4but not of Fig. 5) ,coil |81, closed contacts |05 and conductor ||5 to conductor 88 and co1- lector 38. The current for energizing coils |06 and |01 comes from collectors 31 and 38 without passing through relays 8| and 82. Energizing both of coils |06 and |01 moves the contact bars of these relays such as to maintain an open circuit for contacters 12 and 13, as will be more fully explained subsequently in this specification.

Assuming that the crane is stationary on the bridge and the bridge is intended to move forwardly on the runways (i. e. runway travel), push button |24 is depressed, thereby closing its contacts and connecting bus bar 45 to ground through the following circuit: From collector 68 through conductors and 96, push button |24, conductor |25, and resistor |26 to ground. Inasmuch as bus bar 45 is connected to collector 31 only through coil 85 and reactor B6 of relay 8|, as already described, closing push button |24 energizes coil 85 of relay 8|, thereby closing normally open contacts |04. Resistor |26 is of a sucient value so that when push button |24 is closed, coil 85 draws the necessary current to operate its contacts but does not function as a short circuit to ground for collector 31. Closing push button |24 produces no functioning or relay 82. Closing contacts |04 completes the previously described energizing circuit for coil |00 of relay |08 thereby causing this relay to move its contact bar |21 to close the normally open contacts |28 and opening the normally closed contacts |29. Consequently, a circuit is completed for energizing coil |30 of contacter 12 as follows: From collector 31 through conductors 83 and |3|, closed contacts |28, conductor |32, closed contacts |33 of relay |09, conductor |34, normally closed contacts |35, conductor |36, coil |30, conductor |31, normally closed contacts |38, and conductor |39 to conductor 88 and collector 38. Accordingly, coil |30 is energized thereby closing contacts |4|, |42 and |43 of contactor 12 for supplying power to motor 32 from conductors 08 and 83, `the motor circuit being completed by a ground connection as shown. When push button |24 is released its contacts open, thereby cle-energizing coil 85 .of relay 8| and opening contacts |04, coll |06 .becomes de-energized thereby allowing contactbar |21 to open contacts |28 and close contacts |29. This removes energization from coil |30, consequently opening contacts |4|, |42 and |43 and cle-energizing motor 32.

When it is desired to operate the crane bridge along runways and l2 in the reverse direction, push button |44 is closed thereby connecting bus .bar 46 to ground through the circuit including collector 69, conductors 99 and 9.8', push button switch |44, conductor |45 and resistor |46 to ground. Since bus bar 46 is continuallyl energized through relay 82, closing push button |44 connects coil 9| and reactor 92 of relay 82 into circuit between collector 38 and ground, resistor 46 having suilicient value of resistance that coil 9| will be energized without placing a short circuit on the system. Energizing coil 9| by closing push buttom |44 does not energize coil 85,

but closes normally open contacts |65 thereby energizing coil |01 through a circuit previously described. Energizing coil |01 causes contact bar |41 to move from a position closing contacts |33 to a position closing contacts |48. This completes a circuit for a coil |49 as follows: From collector 31 through conductors 83 and I3 I, closed contacts |29, conductor |5|, closed contacts |48, conductor |52, closed contacts |53, conductor |54, coil |49, conductors |55 and |31, normally closed contacts |38, and conductors |39 and 88 to collector 39. Energizing coil |49 closes contacts |56, |51 and |58 (Fig. 4) to energize motor 32 to run in the reverse direction.

Normally closed contacts |53 are opened when coil is energized, and normally closed contacts are opened when coil |49 is energized. Hence, when motor 32 is operating in either direction, the contactor for causing it to operate in the reverse directioncannot be energized. Short circuting of the power system is thereby prevented.

From the description of the structure thus far, it will be apparent that to cause the crane to travel along the crane bridge, push buttons 94 and ||6 are used, depending upon the direction, this causing both relays 8| and 82 to be ener gized, Ywhich in turn causes relays |08 and |09 tobe energized, these latter relays maintaining the energizing circuits for the contactors 12 and i 13 open so that the crane does not move along the runways. But when either push button |24 or |44 is used, a corresponding single one of relays 8| and 82 is energized thereby causing one or the other of relays |08 and |89 to operate, whereby an energizing circuit for one of contactors 12 and 13 is completed.

Referring particularlyto Figs. 5 and 6, it will be noted that the circuit for coil |30, for example, includes the normally open contacts |28 and the normally closed contacts |33 so that when both relays |01 and |68 operate, the circuit to coil |30 remains open, but when relay |08 alone operates a complete circuit for coil |30 is made. Likewise for. coilv|49 the energizing. circuit includes normally closed contacts |29 and normally open contacts |48 so that when-both relays |01 and |08 operate, the energizing circuit for coil |43 remains open. However, when relay coil 01 alone is energized, contacts |48 are closed and a complete energizing circuit for coil |49 is made.

When both relays |08 and |09 are energized, as when the crane is traveling along the bridge, both coils and 9| are energized since these coils control contacts |04 and |05. Then, when push button switch 94, for example, is opened to cle-energize coils 85 and 9|, these coils do not always permit contacts |04 and |05 to open simultaneously, this being due to residual magnetism in the iron circuits of coils 05 and 9| and other ordinary differences between relays 8| and.82. If contacts |04 and |05 do not open simultaneously, the one remaining closed, for example |04. will permit relay coil |06 to remain energized thereby maintaining contacts |28 closed and consequently completing a circuit for coil. |30, .as already described. This, of course, energizes motor 32 so that the crane starts to travel along the runways. As soon as relay |06 de-energizes. however, this movement stops. The result is that the crane may give a jerk in one direction or the other along the runway when the crane traveling on the bridge is stopped or when the hoist motor is stopped.

This phenomenon is prevented by the provision of relays |59 and |6| (Figs. 4 and 5). Relay |59 includes a coil |62 and normally open contacts |63, coil |62 being connected in parallel with coil |61 and consequently being energized whenever coil |61 is energized to close contacts |63. Similai-ly, relay |6| includes a coil |64 and normally open contacts |65, coil |64 being connectedin parallel with coil |66 and consequently being energized at the same time that coil |06 is energized to close its normally opencontacts |65. Whenever both coils |62 and |64 are energized (that is, when both relays 8| and 82 are energized), contacts |63 and |65 complete additional energizing circuits for coils |66 and |01. Conse quently, should either of contacts |04 and |05 Open before the other, the additional energizing circuits maintain coils |66 and |01 energized until the second of the contacts |04 and |05 open. Referring particularly to Fig. 5, the circuits for energizing coils- |62 and |64 may be. traced as follows: From conductor 88 through conductor H5, contacts |05, conductor |66, coil1|62, conductors |61 and ||4 to conductor 83. VFrom conductor 88 through conductor ||3, contacts |04. conductor ||2, conductor |69, coil |64, and conductors 68 and to conductor 83.

When both contacts |64 and |05 are closed (coils |62 and |64 are energized to close contacts |63 and |65), the additional circuits for energizing coils |06 and |01 may be traced as follows: From conductor 83 through conductor coil |66, conductors |69 and |1|, closed contacts |85, conductor |12, closed contacts |63, conductors |13 and |66, closed contacts |95, and conductor l5 to conductor 88. From conductor 83 through conductor ||4, coil |01, conductors |66 and |13. closed contacts |63, conductor |12, closed contacts |65, conductors |11, |69 and ||2, closed contacts |04, and conductor l I3 to conductor 88. It will be observed from the circuits just traced that when contacts |04 are open, as when relay 8| opens prior to relay 82 (contacts |05 remaining closed), there is a completed circuit for coils4 |06 and |01 which accordingly remain energized. However, under this condition when contacts 05 open, as when relay 82 becomes cle-energized, the

additional circuit traced out for coil |06 as well as the regular circuit for coil |01 open, and consequently both relays |06 and |01 become deenergized simultaneously. The reverse situation occurs of course when contacts open first. In other words, when both relays 8| and 82 are energized, the coil |86 and |01 become de-energized only when the second of relays 8| and 82 opens its contacts. Consequently, there can be no transfer of control from the bridge tr-avel motor 55 to runway travel motor 32, and consequently jerking is prevented.

Relays 8| and 82 operating on low currents as well as high currents are sensitive in their operation to the amount of residual magnetism r-emaining in the coils whenever the relay circuits are broken. When the coils are drawing high amperage the residual magnetism may delay or prevent the relays from dropping out. This may be envisioned as when the current is interrupted at the peak of the alternating current wave. To prevent this from occurring, resistors |14 and |15 are connected in circuit respectively with coils 85 and 8|. Thus (Fig. 5) a circuit may be traced from conductor 83 through conductor 84, coil 85, conductor |16, resistor |14, and conductors |11 and 89 to conductor 88. Since conductors 83 and 88 are continually energized, it will be apparent that coil 85 is continually receiving alternating current energization, resistor |14 being sufficiently large so that this current is not sufiicient to cause relay 8i to pick up. The small amount of current .which flows, however, does effectively reduce residual magnetism. Likewise, (Fig. 5) a circuit, may be traced from conductor 83 through conductor |18, resistor |15, conductor 19, coil 9|, and conductor 89 to conductor 88. Thus, it is seen that coil 9| has a circuit whereby a small amount of current is always flowing therethrough to reduce the residual magnetism.

In comparing Figs. 4, 5 and 6, all conductors are not always shown in each figure since Figs. 5 and 6 are simplied so that each circuit may be seen individually.

From the foregoing description it will be seen that the bus bars or conductors 45 and 46, together with bridge member 2|, supply current to bridge travel motor 55, and at the same time supply the circuits for controlling the energization not only of bridge travel motor 55, but of runway travel motor 32. Accordingly, the need for supplying additional bus bars for control purpose has been obviated. Likewise, the need for separate conductors from control box for motor 32 to control station 1| has been obviated. In some prior constructions these flexible conductors hung in a loop between the control box of motor 32 and control station 1|. In such constructions, of course, the crane could not move from the bridge onto the spur runway I5, for example, except up to the length of such conductors.

With the structure as described, the crane can move olf of bridge member 2| and onto any spur runway, for example spur runway l5, inasmuch as the conductors 41 and 48 may line up directly 10 in virtually all instances inasmuch as the crane will usually return from spur runway and onto the bridge.

To insure that runway travel motor 55 may not be energized while there is no crane on the bridge, normally closed contacts |38, in series with both coils |38 and |49, is provided (coils |30 and |88 controlling energization of motor 32). Whenever the crane moves off of the bridge and onto a spur runway, the normally closed contacts |38 are opened, the contacts being in the form of a limit switch, for example. With contacts E88 open, runway travel motor 32 may not be energized. When the crane returns onto the bridge, contacts |38 are closed and thereafter motor 32 may be energized by manipulating the push button at control station 1|.

When the crane is on a spur runway and its collectors 68 and 68 are running on bus bars 41 and 48, the various circuits traced out for motor 55, as well as the control circuits for contactors 15 and 15, are completely operative inasmuch as bus bars 41 and 48 are energized. This may be visualized from Fig. 4 by noting that the structure within the rectangle ISI embodies all of the control equipment for and including motor 55.

The control for hoisting motor 6| has not been shown in detail inasmuch as it is a duplicate for that of motor 55. Accordingly, motor 6| and its control apparatus is shown schematically as embodied in the rectangle |82 of Fig. 4, push buttons |83 and |84 being provided at control station 1| for controlling lowering and raising of hook 54 by motor 6|. Push buttons |83 and |84 control motor 8| through a circuit arrangement extending from collectors 58 and 68 in identical fashion to motor 55.

- While particular embodiments of the invention have been shown, it will be understood, of course, that the invention is not limited thereto since many modicationsmay be made, and it is, therefore, contemplated by the appended claims to cover any such modications as fall within the true spirit and scope of the invention.

Having thus described the invention, what is claimed and desired to be secured by Letters Patent is:

l. A three-conductor control system comprising, a pair of responsive means connected to one pair of said conductors, first energizing means, means connecting said pair of responsive means in circuit with said rst energizing means whereby said first energizing means performs one control function, second energizing means, means connecting one of said pair of responsive means to a second pair of said conductors for effecting energization of said second energizing means to perform a second control function, and means actuated by the other of said pair of responsive means when energized for preventing energization of said second energizing means.

2. A three-phase, three-conductor control system comprising, a pair of responsive means connected to one pair of said conductorsiirst energizing means, means connecting said pair of responsive means in circuit with said rst energizing means whereby saidvirst energizing `rneans performs one control function, second energizing means, means' connecting one of said pair of responsive meansto a second pairl of said conductors for effecting energization of said second energizing means to perform a second control function, and means actuated yby the other of said pair of responsive means when energized for preventing energization of said second energizing means.

3. A three-conductor control system comprising, a pair of responsive means connected to one pair of said conductors, first energizable means, means connecting said pair of responsive means in circuit wtih said first energizable means whereby said rst energizable means performs one control function, second energizable means, a circuit having normally open and normally closed contact means serially arranged connecting said second energizable means to a pair of said conductors, said normally open contact means being caused to move to closed position by one of said pair of responsive means, said normally closed contact means being caused to move to open position by the other of said responsive means, and means for'connecting said one of said pair of responsive means to another of said pair of conductors for effecting closure of said normally open contact means.

4. A three-conductor control system comprising, a first energizable means for performing a control function, a pair of energizable means respectively for effecting connection to and disconnection from a pair of said conductors of said first energizable means, a second energizable means for performing a control function connected in open circuit to a pair of said conductors through both of said energizable means, means for closing said open circuit, and means for connecting said connection of one of said pair of energizable means to another pair of said conductors.

5. A three-conductor control system comprising, a rstenergizable means for performing a control function, second energizable means for performing a second control function, a pair of means both of which are responsive when said second energizable means is energized respectively for effecting connection to and disconnection from a pair of said conductors'of said first energizable means, and means for connecting said connection of one of said pair of means to another pair of said conductors.

6. A control system for a crane system including runways, a crane bridge for traveling on said runways, and a crane for traveling on said crane bridge comprising, one pair of conductors spaced along said runways, a second pair of conductors spaced along said crane bridge, said runways and said bridge forming a third conductor, a pair of responsive devices in circuit respectively with said second and said first pairs of conductors, one energizable means on said crane bridgefor controlling to and fro movements thereof on said runways, second energizable means on said crane for controlling to and fro movements thereof on said bridge, means on said crane for connecting said second energizable means to said second pair of conductors, `a circuit having normally open and normally closed contact means operated in response to energization of respective ones of said pair of responsive devices connecting said one energizable means to said first pair of conductors, and means on said crane for connecting cach one of said second pair of conductors individually to said third conductor.

7. A control system for a crane system including runways, a crane bridge for traveling on said runways, and a crane for traveling on said crane bridge comprising, one pair of conductors spaced along said runways, a second pair of conductors spaced along said crane bridge, said runways and said bridge forming a third conductor, collectors on said bridge engaging said first pair of con- 12 ductors, a pair of responsive devices in circuit between respective ones of said second pair of conductors and said collectors, one energizable means on said crane bridge for controlling to and fro movements thereof on said runways, second energizable means on said crane for controlling to and fro movements thereof on said bridge, means on said crane for connecting said second energizable means to said second pair of conductors, a circuit having normally open and normally closed contact means operated in response'to energization of respective ones of said pair of responsive devices connecting said one energizable means to said collectors ahead of said responsive devices, and means on said crane for connecting each one of said second pair of conductors individually to said third'conductor.

8. A crane system including runways, a crane bridge for traveling on said runways, and a crane for travelingl on said crane bridge comprising, one motor on said crane bridge for driving said crane bridge to and fro on said runways, a second motor on said crane for driving said crane to and fro on said crane bridge, one pair of conductors spaced along said runways, a second pair of conductors spaced along said crane bridge, said runways and said bridge forming a third conductor, collectors on said crane bridge engaging said first pair of conductors, a pair of responsive means in circuit between respective ones of said second pair of conductors and said collectors, one energiaable means on said crane bridge for connecting said one motor to said collectors ahead of said responsive devices, second energizable means on said crane for connecting said second motor to said second pair ofv conductors, means on said crane for connecting said second energizable means to said second pair of conductors, a circuit having normally open and normally closed contact means operated in response to energizetion of respective ones of said pair of responsive devices connecting said one energizable means to said collectors ahead of said responsive devices, and means on said crane for connecting each one of said second pair of conductors individual- 1y to said third conductor.

9. A crane system including runways, a crane bridge for traveling on said runways, and a crane for traveling on said crane bridge comprising, one motor on said crane bridge for driving said crane bridgey to and fro on said runways, a second motor on said crane for operation thereof, one pair of conductors spaced along said runways, a second pair of conductors spaced along said crane brdige, said runways and said bridge forming a third conductor, collectors on said crane bridge engaging said rst pair of conductors, a pair of responsive means in circuit between respective ones of said second pair of conductors and said collectors, one energizable means on said crane bridge for connecting said one motor to said collectors ahead of said responsive devices, second energizable means on said crane for connecting said second motor to said second conductors, means on said crane for connecting said second energizable means to said second conductors, a circuit having normally open and normally closed contact means operated in response to energization of respective ones of said pair of responsive devices connecting said one energizable means to said collectors ahead of said responsive devices, and means on said crane for connecting each one of said second pair of conductors individually to said third conductor.

10. A crane control system including runways,

a crane bridge ior traveling on said runways, and a crane for traveling on said crane bridge comprising, one pair of conductors spaced along said runways, a second pair of conductors spaced along said crane bridge, said runways and said bridge forming a third conductor, a pair of responsive devices on said bridge in circuit respectively with said second and said first pairs of conductors, one energizable means on said crane bridge for controlling to and fro movements thereof on said runways, second energizable means on said crane for controlling thereof on said bridge, means on said crane for connecting said second energizable means to said second pair of conductors, thereby to energize both said responsive means, a circuit having normally open and normally closed contact means connecting said one energizable means to said first pair of conductors, a pair of operating means for said normally open and closed contact means controlled by energisation of respective ones of said pair of energizable means, means on said crane for connecting each one of said second pair of conductors individually to said third conductor, and means ass cia-ted with said pair of operating means for assuring simultaneous operation thereof when both said pair of energizable means become cle-energized.

11. A crane control system including runways, a crane bridge for traveling on said runways, a spu runway adapted to come into registry with said crane bridge, and a crane or traveling on said crane bridge and said spur runway cornprising, a pair of conductors spaced along said runways, a second pair of conductors spaced along said crane bridge, a third pair of conductors spaced along said spur runway, said runways and said bridge forming a third conductor, a pair of responsive devices on said bridge in circuit respectively with said second and said rst pairs of conductors, one energizable means on said crane bridge for controlling to and iro movements thereof on said runways, collectors on said crane for engaging said second and said third pairs of conductors, second energizable means on said crane for controlling thereof on said bridge and said spur runway, means on said crane for connecting said second energizable means to said collectors, thereby to energize both said responsive means, a circuit having normally open and normally closed contact means connecting said one energizable means to said first pair of conductors, a pair of operating means for said normally open and closed contact means controlled by energization of respective ones o said pair of energizable means, means on said crane for connecting each one of said second pair of conductors individually to said third conductor, and means associated with said pair of operating means for assuring simultaneous operation thereof when both said pairs of energizable means become cle-energized.

RALPH 'W SPAEFORD.

CES

The foilowing references are of r cord in the file of this patent:

UNETED STATES PATENTS 

